Hi AcuDefTechGuy,
To the less educated in speaker numbers like myself, who does this all mean?
The first lesson is that measurements don't tell you everything; the final test is the actual audition of the speakers.
But the measurements of the frequency response gives us a clue as to how accurate the speakers are.
The whole audio spectrum is 20Hz-20kHz, but the "critical" audible spectrum is 200Hz-10kHz.
Within this range, speakers that have a tolerance of +/-3dB are said to be accurate per industry standards. If they have a +/-2dB, that is even better.
So those Aperion speakers are all within +/-3dB tolerance, which means they are fairly accurate on-axis and up to 15 degrees off-axis.
But..... these measurements do not give us the extremely important off-axis (60 degrees horizontal Polar Response) responses, which are as important, if not more important.
Soundstage/Canada NRC, Stereophile, and Audioholics will give you better information as far as the Polar Response (off axis).
Take home message, if you want a speaker that measures accurately, the on-axis FR needs to be no more than +/-3dB 200Hz-10kHz, and the 60 degrees horizontal off-axis needs to be no more than +/-6dB 200Hz-10kHz IMO.
Not many speakers will have a +/-3dB @ 60 degrees off-axis from 200Hz-10kHz.
Unfortunately, a lot of speakers will be +/-12dB or worse @ 60 degrees off-axis.